Model disappears above and below origin of armature when I run gltf made in blender on three.js
The model is probably being culled incorrectly, when the renderer believes it may be offscreen. You can disable that entirely...

model.traverse((object) =&gt; {
  if (object.isMesh) object.frustumCulled = false;
});


... although you'll lose the performance benefit of not rendering the object when it's offscreen. An alternative is to manually increase the size of the bounding box:

model.traverse((object) =&gt; {
  if (object.isMesh) {
    object.geometry.computeBoundingBox();
    object.geometry.boundingBox.expandByScalar(2);
  }
});


The root of the issue is that the skinning animation happens on the GPU, and the renderer needs to cull objects that aren't visible before drawing them on the GPU. So the animation isn't taken into account in that process currently. Sometimes the skinning data changes the scale of the object, not just its pose, which would exacerbate the problem. More details in https://discourse.threejs.org/t/object-bounds-not-updated-with-animation/3749.

threejs r116